Synthesis of Salicylic Acid from Wintergreen Oil

Introduction

This lab's purpose was to determine whether Salicylic Acid made from methyl salicylate is the same as Salicylic Acid made from benzene. This information can be found by comparing the difference in melting points of the two samples of Salicylic Acid.

Here are the physical properties of Salicylic Acid and the mechanism of reactions that occurred in this lab.

How Salicylic Acid is derived:

Procedure/Results

First, .26mL of 2.0mmol methyl Salicylate was measured and put into a reaction vial along with 2.5mL of 6M NaOH and a stir bar. The sample became a cloudy white color. The reaction vial was then connected to a reflux heating set-up and allowed to boil for twenty minutes until the cloudy white color dissolved into a clear liquid and then was allowed to cool. The sample was then transferred to a medium size beaker and slightly less than 2.5mL of sulfuric acid was added to the sample to adjust to pH 2. It was then placed in an ice bath to promote crystallization and then vacuum filtered to produce a white solid. The Salicylic Acid was the purified by adding 3mL of boiling water and then re-crystallization by placing it in an ice bath and vacuum filtering it. The sample was allowed to dry for a few minutes and then weighed. The weight was found to be .10g. The sample was then divided into two equal portions and one portion was mixed with the given sample of Salicylic Acid (made from benzene). Both samples where then tested in capillary tubes to calculate the melting point. The result of this step is represented in the chart below:

Table 1 - MELTING POINT RANGE OF SAMPLES

Sample Range (in degrees Celsius)

Salicylic Acid (made methyl Salicylate in this lab) 157-160

Salicylic Acid (mixed with provided sample) 158-160

Discussion

According to the physical properties of Salicylic Acid, pure Salicylic Acid has a melting point of about 159 degrees Celsius. Since both samples of Salicylic Acid were found to